Dresden 2006 – scientific programme
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TT: Tiefe Temperaturen
TT 26: Transport - Poster Session
TT 26.19: Poster
Wednesday, March 29, 2006, 14:30–18:30, P1
SIS and SIFS niobium Josephson junctions for superconducting flux qubits — •Georg Wild, Bernhard Huber, Tobias Heimbeck, Karl Madek, Matteo Mariantoni, Achim Marx, and Rudolf Gross — Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany
Superconducting loops containing Josephson junctions (JJ) are among the most promising candidates for the implementation of quantum computation systems. Unfortunately, the operation point of such a persistent current qubit (PCQB) is around half an applied flux quantum, which is hard to be applied stably and uniformly for systems consisting of a large number of PCQBs. A possibility to circumvent this problem is to insert π-phase-shift elements into the qubit loop. These may be implemented by superconductor/ferromagnet/superconductor (SFS) JJ, where the correlated electron-hole-pairs created by Andreev reflection are modified by the magnetic exchange interaction.
The quality of niobium based Josephson junctions depends crucially on the properties of the relevant interfaces. Therefore, we have developed an in-situ multilayer process to prepare Nb/AlOx/Ni0.18Pd0.82/Nb stacks. A mesa is defined in the top layers using optical lithography and RIE. After deposing an isolating SiO2 layer the top niobium electrode is contacted.
Transport measurements on SIS and SIFS junctions have been performed to characterize Josephson coupling.
This work was supported by the Sonderforschungsbereich 631 of the Deutsche Forschungsgemeinschaft.